1. Field of the Invention
This invention concerns reactors for heterogeneous synthesis, and moe particularly for the catalytic synthesis of ammonia, methanol, fuel and higher alcohols, monomers and similar substances, consisting of an outer shell, an internal cartridge comprising a solid wall forming an air space with the inside wall of the shell, at least one catalytic bed containing granular catalyst arranged between a bottom and two concentric cylindrical walls of which the outer wall is perforated for the whole of its axial length and the inner wall is unperforated along a small part; of means for feeding the reaction gas, of means to extract reacted gas, of at least one heat exchanger, and of the means to feed to the latter fresh exchange gas.
2. Description of the Prior Art
Reactors of this type are described in the Applicant's U.S. patent application Ser. No. 162,436 now U.S. Pat. No. 4,372,920; they are characterised by the fact that each layer or catalyst bed is run through by reaction gas in one zone with prevalently axial flow, and in another zone with prevalently radial flow, the prevalently axial flow zone acting also as sealing pad between catalyst layers. Preferably the cartridge is advantageously obtained by simply assembling the cartridge modules, each formed (going from the outside towards the inside) by a cylindrical solid side wall, by a solid bottom which may be the continuation of the external solid wall, by a first cylindrical wall perforated for the whole of its axial length and by a cylindrical internal wall perforated only in part, namely having at least a small axial length unperforated: the catalyst bed is arranged on said bottom and said delimited by the said lateral walls fully respectively partially perforated. Each layer or catalyst bed is open at the top where the prevalently axial flow zone acts as sealing pad. Moreover, there is always a separation zone between catalytic beds to which is sent the cold gas to be used for exchanging heat (directly or indirectly) with the preheated and/or already partly reacted gas.
In the case of indirect heat exchange, the heat exchanger between cold synthesis gas and partly reacted hot synthesis gas is arranged axially to the reactor in the central part of the catalytic layers: the tubes of these single exchangers are run through internally by the cold feed gas and are lapped externally by the hot gas which has flowed (axially and radially) through the catalytic bed wrapping the exchanger in question, as well as the catalytic layer or layers preceding it. It may be also anticipated that U.S. Pat. No. 4,181,701 describes a reactor with exclusively radial flow and centrally arranged heat exchanger.